<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style> li {
        background-color: aqua;
        width: 100px;
        height: 20px;
        float: left;
    }

    .cl {
        clear: both;
    }
       
    </style>
</head>
<body>
<div>
    <ul>
    <li>a</li>
    <li>b</li>
    <li>c</li>
    </ul>
    <div class="cl"></div>
</div>
<div>
    <ul>
        <li>1</li>
        <li>2</li>
        <li>3</li>
    </ul>
</div>
</body>
</html>